This invention relates to epidural catheters.
Epidural catheters are used to introduce anaesthetic fluid into the epidural space. The effectiveness of the anaesthesia block produced is dependent on the anaesthetic being administered in the correct location. Conventional epidural catheters are straight and flexible. They are usually closed at the tip and have several side openings through which fluid can emerge from the catheter. It has been found that, if the tip of the catheter is inserted more than about 10-20 mm into the epidural space, the tip seldom remains in the desired location near the site of insertion but passes into the lateral or anterior parts of the epidural space. It is thought that this may sometimes be the reason why epidural anaesthesia occasionally produces imperfect blocks. Some anaesthetists prefer to leave a shorter length of catheter projecting into the epidural space, to reduce the risk of the tip of the catheter moving away from the insertion site. However, if an insufficient length of catheter projects into the epidural space, movement between the skin and ligamentum flavum can pull the catheter out of the epidural space and result in injection of anaesthetic outside the epidural space.